1. Field of the Invention
The present invention relates to a ribbon cartridge for printing devices including typewriters and printers, and is more particularly concerned with ribbon cartridges which have endless ribbons that are re-inkable.
2. Description of the Prior Art
A problem with a number of conventional ink ribbon cartridges or cassettes in use today with typewriters and printers is that the darkness of the print fades during the life of the ribbon.
In several of the conventional cartridges, the ribbon ink that is being depleted during printing is replenished through a reservoir of ink held in either a foam pad or in a circular foam roll. The ink is transferred onto the fabric ribbon by applying the ink from the foam pad or foam roll to a transfer roller that meters the ink from the transfer roller to the fabric ribbon. This keeps the ink from puddling in one spot on the ribbon when it sits idle between print sessions. However, this structure does not provide a solution to the problem of maintaining a uniform darkness of the print during the life of the ink ribbon cartridge.